foo     => [
    {
        date    => '2008-12-23',
        count   => 1234
    },
    {
        date    => '2008-12-24',
        count   => 1234
    }
],
bar     => [
    {
        date    => '2008-12-23',
        count   => 1234
    },
    {
        date    => '2008-12-24',
        count   => 1234
    }
],
baz     => [
    {
        date    => '2008-12-24',
        count   => 1234
    }
]